Touch sensitive devices are more and more applied to the field of display technology. When a user touches a touch screen of a touch sensitive device through his finger, the touch sensitive device can sense the touch position of the finger on the touch screen and a touch pressure of the finger so that human-machine interaction can be obtained through touching images or texts on the touch sensitive screen by the user.
Taking a cell phone as an example of a touch sensitive device, as illustrated in FIG. 1, a cell phone comprises a middle bezel 103 and a touch sensitive screen 100 mounted on the middle bezel 103. In order to detect a touch pressure by a finger, the cell phone further comprises a first electrode 101 and a second electrode 102 disposed opposite to the first electrode 101, the first electrode 101 and the second electrode 102 forming a capacitor. When a user touches the touch sensitive screen 100 with various touch forces, different deformations occur to the touch sensitive screen 100, which makes the distance between the first electrode 101 and the second electrode 102 and further the capacitance of the capacitor changes. Thus, the touch force on the touch sensitive screen can be measured by detecting variation of the capacitance.
However, when touching the touch sensitive screen, no matter how much fingers press on the touch sensitive screen, only the force strength can be tested by detecting variation in the distance H between the first electrode 101 and the second electrode 102, and the number of fingers touching the touch sensitive screen cannot be determined. Thus, different commands cannot be triggered in cases of pressing the touch sensitive screen through one or more fingers, that is to say, multi-touch cannot be achieved, and commands for touch are limited.